Currently available semiconductor memory device products may roughly be divided into two types: stationary products receiving unlimited power from a power supply, and portable products relying on pre-supplied power. Since the stationary products may have unlimited power from a power supply, improving efficiency may be more important than lowering power consumption. In contrast, lowering power consumption may be more important for portable products, since the portable products generally rely on batteries, which usually have a limited power supply. That is, although both the portable and the stationary products may pursue higher efficiency, larger integration, and lower power consumption, the development of portable products may be more focused on lowering power consumption while the development of stationary products may be more focused on improving efficiency.
For example, a stationary semiconductor memory device may use a double data rate 3 (DDR3) dynamic random access memory (DRAM), while a portable semiconductor memory device may use a mobile double data rate (MDDR) DRAM. In this case, it may be more difficult to lower power consumption of the stationary device using the DDR3 DRAM than that of the portable device using the MDDR DRAM, even if the stationary device is imparted with mobility. On the other hand, it may be more difficult to improve efficiency of the portable device using the MDDR DRAM than that of the stationary device using the DDR3 DRAM, even if unlimited power is supplied in a manner similar to the stationary device.
In this regard, it may be necessary for the stationary device to lower power consumption in the manner of the mobile device, and for the portable device to operate with higher efficiency while receiving unlimited power from a power supply in the manner of the stationary device.